Jessica had a crush on her manager, but she’d managed to keep it under wraps. That is, until the office party ... and several glasses of Merlot. Suddenly it seemed like the perfect time to unburden her tortured soul. And unburden she did, to everyone in the room — including the man’s wife. Not surprisingly, this turned a professional holiday gathering into an excruciating and career-limiting event.

The holiday office party offers a great opportunity to socialize with co-workers and develop or deepen relationships. It’s a wonderful time to mingle with colleagues in a less pressured setting. It might give you a chance to personally thank those who have been helpful or supportive throughout the year. It could even be an opportunity to meet with senior executives, either to introduce yourself or get to know them on a more informal level.

The desire to relax and have fun — especially in these challenging economic times — can be a highly anticipated, positive antidote to workplace stress. But when you combine the need to let your hair down with too many glasses of wine or cocktails, it’s a mix that can cause trouble. You may forget that this is not the time to rant about the depreciated value of your 401K, tell the latest off-color joke, or do your wicked impression of the CEO, even if you’ve totally nailed her southern drawl. In fact, those kinds of inappropriate remarks (as well as confessing your innermost secrets as Jessica did) may not only cost you a promotion, but quite possibly a job.

And watching what you say is only part of the challenge. Another personal dynamic you should be aware of is the impact of your body language. In all workplace situations, including after-hours parties, your nonverbal behavior speaks volumes. The trick is to physically embody the messages that you want delivered. Here are some body language tips that will help your holiday office party be a personal and professional success for you:

Develop an inclusive, welcoming attitude. Pretend that you are the party’s host or hostess, and that your job is to make others feel welcome and at ease. Approaching people with this attitude will immediately resonate in a positive way.

Stand tall. Your mother was right (again!) when she told you to stand up straight. As you pull your shoulders back and hold your head high, you assume a posture of confidence and self-esteem.

Shake hands — but don’t go overboard. The way you greet your fellow party-goers can have a huge impact on their perception of you. A firm handshake is a business skill worth developing, and a light touch on the arm or shoulder can create an instant bond. But if you hang on people or touch them too frequently, you send unintended signals of neediness or flirtation.

Let your body show that you are at ease. If you want people to see you as comfortable and approachable, assume an open position with your legs about shoulder width apart and your arms loosely at your side. Don’t cross your arms and legs or use objects (your drink or plate of food) as a barrier. It looks as if you are closed off or resistant.

Mirror the other person’s gestures and expressions. When we meet others for the first time, subconsciously we scan the other person’s body to see if they move or gesture in a similar way to us. When you subtly mimic the person you are speaking to, it is a way of silently saying, “We are alike. We feel the same and have the same attitudes.”

Smile. A smile is an invitation, a sign of welcome. Smiling directly influences how other people respond to you. The human brain prefers happy faces, recognizing them more quickly than those with negative expressions. In fact, research shows that if you smile at someone, it activates the “reward center” in that person’s brain. It is also a natural response for the other person to smile back at you.

Make positive eye contact. Looking at someone’s eyes transmits energy and indicates interest and openness. (To improve your eye contact, make a practice of noticing the eye color of everyone you speak with at the party.)

Lean in slightly. Leaning forward shows you’re engaged and interested, but also be respectful of other people’s space. Although this varies by culture, in North American business situations, even in a party setting, that means staying at least 18 inches away.

Use open arm movements and show the palms of your hands. Those gestures are subconsciously evaluated as positive, candid and persuasive. But keep your gestures below shoulder level. Flailing your arms in the air will not look enthusiastic, only erratic.

By all means, attend the holiday office gathering and have a good time. Just remember, you’re at a work-related social event that is just as important as any other business function. Which brings me to my last point: Don’t wear your “club-appropriate attire” to the office party. Women especially should take note and save their strapless, midriff baring, see-through tops and micro-mini skirts for socializing with friends.

Keep these tips in mind and use the office party to make a good impression, show off your sparkling personality, and advance — not derail — your career!